Following BART’s illegal shut down of cell phone service last week to interrupt a protest at San Francisco Civic Center Station, the hacktivist group Anonymous promised to launch a cyber attack against the rapid transit system.

“For the people outside of San Francisco, show solidarity by using black fax, email bombs, and phone calls to the BART Board of Directors. BART decided to cut off your communications and now we will flood theirs,” the group said in a statement.

Anonymous calls the effort #OpBART. The statement includes links to media materials and “email and fax bomb info.”

The BART cell phone shutdown occurred on Thursday and took out service from 4 p.m. to 7 p.m. PST at the Embarcadero, Montgomery Street, Powell Street, and Civic Center BART stations.

“Shutting down access to mobile phones is the wrong response to political protests, whether it’s halfway around the world or right here in San Francisco. You have the right to speak out. Both the California Constitution and the First Amendment to the United States Constitution protect your right to free expression,” the ACLU said following the outage, a violation of the Communications Act of 1934.

The outrageous BART action follows a call by British PM David Cameron to censor social media in response to riots in London. Cameron said the “free flow of information” can be a problem and promised the government will work with business to shut down internet and cell phone communications in the future.

Home Secretary Theresa May called for meetings with the three companies following Cameron’s statement.

BART’s cell phone shutdown reveals government will also preemptively strike media – like the dictator Mubarak did in Egypt before he was deposed – for political reasons.

Cameron set a precedent that will not be used by government to silence critics and the political opposition.